The present invention relates to neurostimulation systems, such as a spinal cord stimulation (SCS) system, and more particularly to a method for determining the relative position and orientation of electrodes on a neurostimulation lead or leads used with such a system.
In SCS systems, positioning of the leads is critical to the success of the therapy. During surgery, the physician places the leads in a very careful manner in order to locate the electrodes proximal to neural elements that are the target of the stimulation. During and after placement, stimulation energy is delivered to verify that the leads are indeed stimulating the appropriate neural elements.
However, if the leads happen to shift position, the targeted neural elements may no longer be appropriately stimulated. At best, this can require electrical reprogramming to restore therapy or, at worst, surgical revision, where a second surgery is required and the leads must be manually readjusted. In the first case, physician may have only a suspicion that a lead has shifted position, based on patient reporting of paresthesia, which is not foolproof. Also, attempting to program the leads based on paresthesia locations can be challenging.
What is needed is a more objective technique for verifying the position of the leads.
Prior art approaches for determining the lead position are disclosed in U.S. Pat. Nos. 4,486,835; 4,539,640; and 5,184,624, which patents are incorporated herein by reference.